In a typical wireless communication network, wireless devices, also known as wireless communication devices, mobile stations, stations (STA) and/or user equipments (UE), communicate via a Radio Access Network (RAN) to one or more core networks (CN). The RAN covers a geographical area which is divided into service areas or cell areas, which may also be referred to as a beam or a beam group, with each service area or cell area being served by a radio network node such as a radio access node e.g., a Wi-Fi access point or a radio base station (RBS), which in some networks may also be denoted, for example, a “NodeB” or “eNodeB”. A service area or cell area is a geographical area where radio coverage is provided by the radio network node. The radio network node communicates over an air interface operating on radio frequencies with the wireless device within range of the radio network node.
A Universal Mobile Telecommunications System (UMTS) is a third generation (3G) telecommunication network, which evolved from the second generation (2G) Global System for Mobile Communications (GSM). The UMTS terrestrial radio access network (UTRAN) is essentially a RAN using wideband code division multiple access (WCDMA) and/or High Speed Packet Access (HSPA) for user equipments. In a forum known as the Third Generation Partnership Project (3GPP), telecommunications suppliers propose and agree upon standards for third generation networks, and investigate enhanced data rate and radio capacity. In some RANs, e.g. as in UMTS, several radio network nodes may be connected, e.g., by landlines or microwave, to a controller node, such as a radio network controller (RNC) or a base station controller (BSC), which supervises and coordinates various activities of the plural radio network nodes connected thereto. This type of connection is sometimes referred to as a backhaul connection. The RNCs and BSCs are typically connected to one or more core networks.
Specifications for the Evolved Packet System (EPS), also called a Fourth Generation (4G) network, have been completed within the 3rd Generation Partnership Project (3GPP) and this work continues in the coming 3GPP releases, for example to specify a Fifth Generation (5G) network. The EPS comprises the Evolved Universal Terrestrial Radio Access Network (E-UTRAN), also known as the Long Term Evolution (LTE) radio access network, and the Evolved Packet Core (EPC), also known as System Architecture Evolution (SAE) core network. E-UTRAN/LTE is a variant of a 3GPP radio access network wherein the radio network nodes are directly connected to the EPC core network rather than to RNCs. In general, in E-UTRAN/LTE the functions of an RNC are distributed between the radio network nodes, e.g. eNodeBs in LTE, and the core network. As such, the RAN of an EPS has an essentially “flat” architecture comprising radio network nodes connected directly to one or more core networks, i.e. they are not connected to RNCs. To compensate for that, the E-UTRAN specification defines a direct interface between the radio network nodes, this interface being denoted the X2 interface. EPS is the Evolved 3GPP Packet Switched Domain.
Positioning
At RAN #72 a Work item on “Positioning Enhancements for GSM EDGE Radio Access Network (GERAN)” for realizing improved accuracy was approved. EDGE is the abbreviation for Enhanced Data Rates for GSM Evolution. In this work idem a candidate method for realizing improved accuracy is specified wherein a Mobile Station (MS) performs Timing Advance (TA) multilateration, see Positioning Enhancements for GERAN, which relies on establishing the position of the MS based on TA values in multiple cells. This procedure of TA multilateration is also referred to as Multilateration Timing Advance procedure.
At RAN1#86 a proposal based on a similar approach was made also to support positioning of Narrow Band-Internet of Things (NB-IoT) mobiles.
TA is a measure of the propagation delay between a base transceiver station (BTS) and the MS, and since the speed by which radio waves travel is known, the distance between the BTS and the MS can be derived. Further, if TA is measured to multiple BTSs and the positions of these BTSs are known, the position of the MS can be derived. Measurement of TA requires that the MS synchronizes to each neighbor BTS and transmits a signal time-aligned with the timing of the BTS, estimated by the MS. The BTS measures the time difference between its own time reference, and the timing of the received signal. This time difference is equal to two times the propagation delay between the BTS and the MS (one propagation delay of the BTS's synchronization signal to the MS, plus one equally large propagation delay of the signal transmitted by the MS back to the BTS).
Once the set of TA values are established, the position of the device can be derived through so called Multilateration where the positions of the device such as an MS is determined by the intersection of a set of hyperbolic curves associated with each BTS, see FIG. 1. FIG. 1, Illustrates a Multilateration involving three base stations associated with three timing advance values for a device.
The calculation of the position of the device is typically carried out by a positioning node such as e.g. a Serving Mobile Location Centre (SMLC) which implies that all of the derived timing advance and associated BTS information needs to be sent to positioning node that initiated the procedure.
For the purpose of simplifying the descriptions provided herein the following definitions are used:
Foreign BTS: A BTS associated with a BSS that uses a positioning node that is different from the positioning node used by the BSS that manages the cell serving the MS when the positioning procedure is initiated. In this case the derived TA information and identity of the corresponding cell are relayed to the serving positioning node using the core network (i.e. in this case the BSS has no context for the MS).
Local BTS: A BTS associated with a different BSS but still a BSS that uses the same positioning node as the BSS that manages the cell serving the MS when the positioning procedure is initiated. In this case the derived timing advance information and identity of the corresponding cell are relayed to the serving positioning node using the core network (i.e. in this case the BSS has no context for the MS).
Serving BTS: A BTS associated with a BSS that manages the cell serving the MS when the positioning procedure is initiated. In this case the derived timing advance information and identity of the corresponding cell are sent directly to the serving positioning node (i.e. in this case the BSS has a context for the MS).
Serving SMLC node: The SMLC node that commands a MS to perform the Multilateration procedure, i.e. it sends the Radio Resource Location services (LCS) Protocol (RRLP) Multilateration Request to the MS).
Serving BSS: The BSS associated with the serving BTS (i.e. the BSS that has context information for the TLLI corresponding to a MS for which the Multilateration procedure has been triggered).
Non-serving BSS: A BSS associated with a Foreign BTS (i.e. a BSS that does not have context information for the TLLI corresponding to a MS for which the Multilateration procedure has been triggered).
A Connection-oriented message requires a session connection to be established before any data can be sent. This method is often referred to as a reliable network service, since it may guarantee that data will arrive in the same order.
A Connectionless message on the contrary, does not require a session connection between sender and receiver. The sender simply starts sending packets to the destination. This service does not have the reliability of the connection-oriented method, but it is useful for periodic burst transfers. A connectionless network provides minimal services.
Internet of Things
It is expected that in a near future, the population of Cellular Internet of Things (IoT) devices such as MSs will be very large. Various predictions exist, among which can be mentioned that assumes >60000 devices per square kilometer, and that assumes 1000000 devices per square kilometer. A large fraction of these devices are expected to be stationary, e.g., gas and electricity meters, vending machines, etc.
Extended Coverage (EC)-GSM-IoT and Narrow band (NB)-IoT are two standards for Cellular IoT specified by 3GPP TSG GERAN and TSG RAN.